Rotary pump



July 28, 1942. E, SIBLEY 2,291,354

ROTARY PUMP Filed July 29, 1940 2 Sheets-Sheet 1 July 28, 1942. slBLEY2,291,354

ROTARY PUMP Filed July 29, 1940 2 Sheets-Sheet 2 Patented July 28, 1942no'mnr rum Eugene Sibley, Detroit, Micln, assig'nor, by mesneassignments, to Franklin D. Dougherty, trustee,

Detroit, Mich.

Application July 29, 1940, Serial No. 348,256 9 Claims. (or. 103126) apumping element to permit passage of solid particles without damage tothe pump.

It is a further object of the present invention to provide a gear pumpembodying an lntemal and external intermeshing gear in which one of saidgears is formed of resilient compressible material and of a size suchthat in normal operation a substantially perfect seal is obtained.

It is a further object of the invention to provide a pump of the typedescribed having an annular rotor provided with internal teeth formed ofcompressible, resilient material, the outer surface of said rotor beingcylindrical and formed of. a material adapted strongly to resistdistortion.

It is a further object of the invention to provide a rotor of the typedescribed in which the outer distortion resisting surface terminatesshort of the ends of the member.

It is a further object of the invention to provide a pump of thecharacter described comprising an internally toothed annular gear, adriving pinion meshing with the annular gear, the pinion being modifiedfrom a strict conjugate to the internally toothed annular gear by beingrelieved throughout the spaces between the tips of adjacent teeth.-

It is a further object of the present invention to provide a pump of thecharacter described having meshing pumping gears, at least one of whichis formed of compressible, resilient material, in which means areprovided for adjusting one of said gears in a plane perpendicular to theaxis of,said gears.

Other objects of the invention will be apparent as the descriptionproceeds and when taken in conjunction with the accompanying drawings,and wherein:

Figure 1 is a plan view of my pump with parts broken away for clearness;

Figure 2 is a view corresponding to Figure 1 in which the pumpingelements are moved to a new position;

Figure 3 is a plan view of the casing for my improved pump;

Figure 4 is a section on the line 4-4, Figure 1;

Figure 5 is a section on the line 5 5, Figure 1;

Figure 6 is a perspective of the pumping pinion;

Figure 7 is a perspective of the annular internal gear forming anelement of my pump;

Figure 8 is a side elevation, partly in section, of one embodiment of mypump;

Figure 9 is a section on the line 9-9, Figure 8;

Figure 10 is a transverse section through the annular rotor; and

Figure 11 is a diagrammatic view illustrating a modification preferablyprovided on the driving pinion.

Gear pumps embodying certain features disclosedin the drawings have longbeen known to the art and their principles are well understood. Byproviding an internal toothed annular gear of a certain number of teethin combination with a pinion conjugate to the teeth of the annular gearand meshing internally therewith,

. the pinion having one less tooth than the annular gear and beingmounted eccentrically thereto, a pump is provided which operatesefficiently' and exhibits a number of important properties.

The form of the teeth employed in this type of gear may be widely variedand in general it may be stated that it is necessary only for the teethto be in constant contact.

Certain well known geometric shapes may be employed in the formation ofthe gear teeth, or in some cases one of the elements'may be designed andthe conjugate element may be generated from the first gear selected.

It will be understood that pumps of this type, that is, pumps embodyingan internal gear and an internal meshing and eccentrically mountedpinion have long been known, and the particular form of gear toothemployed forms no part of the present invention.

On the other hand, the present invention relates particularly to thematerial employed and may be practiced with various forms of gears.

In the figures, I have disclosed an embodiment of my invention in whicha pump casing I0 is provided with a central bushing II in which isrotatably mounted a drive shaft l2. The bushing ii extends inwardly andterminates in a flat bearing surface l3 against which the pinion of myimproved gear pump is adapted to rotate.

The casing ill is open at one end and is accurately machined to providea cylindrical recess I H in which is rotatably mounted the annular gearmember i5.

A projection I6 is provided with screw threads l1 and a sealing cap i8is adapted to fit thereover to'provide in combination with a packing.

26 open, as best shown in Figure 3, into the These openings form'cylindrical chamber ll. inlet and outlet to the pump according to thedirection of rotation.

Figure 7, is received within the cylindrical chamber l4 and is adaptedto closely engage the curved side walls thereof and also the top closureplate 20. The gear member I5 is provided with a number of gear teeth ofsuitable form 21. The annular gear I5 is freely rotatable in thecylindrical chamber I4.

A pinion 30 is keyed or otherwise secured to the drive shaft l2 and hasteeth 3| which are conjugate to the teeth 21 of the annular gear l5.Inthe present embodiment of my invention The annular gear member l5, asbest seen in;

aaamee pends upon a seal being maintained in any chamber 32' between theteeth. In otherwords, as seen in Figure 1,'the tooth of the pinion}?! jshown at the top is in sliding contact with the corresponding tooth ofthe annular gear 15.

This necessary high degree of accuracy. in fin-- ishing also introducedanother unsatisfactory (element into the operation of this type of pumpas constructed in the past.

If fine particles,- such as sand or, grit, werepassed through the pump,these elements would cause damage to the .interengaging surface of thepinion and the gear.

For this reason pumps of this type have not had a wide application,being in the first case extremely expensive to construct and in thesecond case being subject to irreparable damage upon introduction offoreign, matter thereinto.

I have discovered that the-difficulties referred tocan be completelyavoided by forming one of the elements of a resilient material. Theadvantages of this type of construction are numerous the annular gear I5is shown as provided with five teeth, whereas the pinion is shown asprovided with four teeth. The number of teeth need not be as' indicated,the only requirement being that the annular gear be provided with onemore tooth than the meshing pinion.

As best seen in Figures 1 and 2, the pinion and the annular gear mesh soas to provide chambers 32 formed between the intermeshing teeth. As willbe apparent, these chambers expand and contract as the two gears rolltogether.

Furthermore, a gear tooth 3| on the pinion 30 is adapted to remain incontact with the opposed tooth 21 of the annular gear l5 so as toprovide an effective seal for the chambers 32.

It will be noted in Figure 1, that the pinion 30 is mountedeccentrically of the annular gear l5, and if it is assumed that thepinion is positively driven in the direction of the arrow it will beapparent that the chamber 32a is decreasing involume. The valve opening25, indicated in this figure, is in communication withthe chamber 32aand continued rotation of the parts results in the expelling of fluidfrom the chamber 32a through the valve 25 out through conduit 23, whichin this case is the outlet line.

The chamber 32b in Figure 1 is expanding in volume and is incommunication with the valve opening from the valve chamber 26 so thatfluid is being drawn through the inlet line 24. It will be appreciatedthat the shape and areaof the valve openings may be varied withinrelatively wide limits, but the shape indicated in the drawings hasproved highly efficient in operation.

.The driving shaft [2 positively rotates the pinion 30 and this pinionthrough its intermeshing and in order to obtain any satisfactory degreeof efiiciency it was necessary that the parts be finished with extremeaccuracy. This is necesand will be pointed out specifically. Generallyspeaking, either the pinion 30 or the annular gear 15 may be formed ofthe resilient materiaLbut for various reasons it ispreferable to formthe annular gear l5, of the resilient material. numberv of materials maybe employed in the construction of the resilient member, but I havediscovered that highly satisfactory results are obtained when theresilient member is formed of a rubberous material.

The necessity for accurate machining of the parts is avoided byemploying rubber. more, it is possible to obtain a much more efficientseal than has hitherto been obtained by forming one of the members ofrubber. The use of rubber as a material for forming the resilient memberalso offers another important advantage in that it may be effectivelylubricated by water when the pump is employed as a water pump.

I have found that the most eilicient results are obtained when theannular member I5 is formed of rubberous material and is madeto fitsnugly without bindingwithin the chamber. Also the annular member I5, ifformed of rubber, is made so as to bear with a slight pressure againstthe-closure plate 20, thus insuring a perfect seal at this point.

In addition to this, the pinion 30 may be made just slightly oversize sothat when placed in mesh with the annular gear 15 the resilientmaterialof the gear I5 is slightly compressed. Thepinion 30 is made of such asize that it bears against the closure plate 20 and forms atight pinion30 as it slides against the corresponding surface of the annular gear l5pushes. a slight wave of the resilient material ahead and thus providesa sealing surface of substantial extent. Due to the material employed,this engagement between the parts does not produce excessive frictionsince the'parts are efficiently lubricated by the fluid being pumped.Even where the pump is employed as an air pump, it has been found thatthe friction resulting from this efficient sealing engagement betweenthe teeth is not excessive.

. Another important advantage of the material specified herein is thatif particles of sand or sarily so because the efliciency'ofthe pump de-Furtherv v This may be readily' ex-' plained bythe fact that each tooth3| of. the

grit pass through the pump they will readily embed themselves in theresilient member and will not cause damage to the metallic member. Thisis to be constrasted with pumps made according to prior teachings inwhich a particle of grit would cause irreparable damage to the surface.In order for pumps comprising'two metallic intermeshing gears to operatewith reasonable emciency, it was necessary for the engaging surface tobe ground or otherwise finished to an extremely high degree of accuracy.

According to the present teachings, inaccuracies in machining the partsdo not seriously affect the efilciency of the pump, since by employing aresilient and slightly compressible material these inaccuracies do notpermit leakage of fluid past the pumping members.

In Figures 8 and 9 I have indicated a complete pump which comprises abase 40 to which is secured a pair of plates 4| and 42. The plate 4|isbolted or otherwise rigidly secured to the base 40 and, as shown inFigure 8, the plate 42 is bolted directly to the plate 4| by bolts 43.Intermediate the plates 4| and 42 is a housing 44, whose shape isindicated best in Figure 9. The housing 44 has an internal cylindricalchamber 45 and is provided with inlet and outlet connections 46 and 41communicating with valve slots 48 and 49. The closure plates 4| and 42have valve openings of the shape indicated generally at 25 and 26 inFigures 1 to 3.

'Ihe internally toothed, annular rotor is indicated in Figure 9 at 50and, as shown in this figure, has a cylinder or sleeve member 5| securedto the outer surface thereof, which will later be described in detail.The member 50 is for the most part formed of resilient, compressiblematerial, such for example as a good grade of rubber, either natural orsynthetic.

The driving pinion is indicated at 52 and is shown in Figure 9 as ininternal meshing relation with the annular member 50. The pinion 52 ispreferably of 'metal, although it may be formed of fiber or othermaterial. The pinion 52 is keyed or otherwise secured to a shaft 53which extends through suitably formed openings in the base 40 and theend plate and is connected to a motor or other suitable drivingmechanism.

The internally toothed annular rotor 50 and driving pinion 52 are madeslightly oversize relative to each other. The amount of oversize may beon the order of a few thousandths of an inch and results in the tips ofthe teeth of the pinion 52 being slightly embedded in the compressible,resilient material of the rotor 50 as indicated for example at 54.

When the term oversize or relatively oversize is employed, it is meantto imply that one or both of the parts is larger than would be possiblefor proper meshing relation if the parts were made of incompressiblematerial. It will be appreciated, of course, that in making aninternally toothed member oversize, the teeth extend farther towards theaxis of the annular member, whereas in making an externally toothedpinion oversize the teeth extend farther from the axis than otherwise.This explanation is given at this time so as to avoid the necessity ofimporting unnecessary and merely explanatory verbiage into the claims.It will further be understood that with the parts relatively oversize asherein described, it is perfectly proper to speak of either part asoversize with respect to the other.

As best seen in Figure 8, the housing 44 is ad- .inss 55 and bolt 43. i

The driving shaft "is supported rigidly by suitable Joumalled bearingsin the frame 44 and end plate 4| so that this adjustment of the housing44 in effect provides for adjustment between the rotor 58 and pinion 52.

This adjustment is permitted by reason of the compressibility of theteeth of one of the parts, preferably the rotor, as will be'readilyapparent. It may be stated in general that this adjustment is useful incompensating for wear between the rotor and the pinion. It has a furtherimportant utility in modifying the pump operation in accordance with thecharacteristics of the fluid being pumped. Thus, for example, if heavyoil or a relatively viscous liquid is being pumped, it will be desirableto adjust the housing and, accordingly, the rotor 50 downwardly relativeto the pinion 52 so as to provide an increasingly eifective seal in thepressure zone. Where water, for example, is being pumped, the oppositeadjustment may be made.

Referring now to Figure 10, I have indicated the annular, internallytoothed rotor 50 as formed generally of a block of compressible,resilient material, such as rubber, and as provided with an integrallyattached cylinder or sleeve 5| of a material adapted strongly to resistdistortion. this is a very important feature of my improved pump. Theresilient, compressible material of which the teeth of the rotor 50 areformed is, of course, subject to distortion, particularly under highpressure. Accordingly, without the provision of the cylinder or sleeve5|, it is found that sometimes the rotor 50 tends to bind in the housing44. Even where actual binding does not occur, the tendency towardsdistortion inherent in the compressible, resilient material increasesfriction to an undesirable degree.

By providing a cylinder or sleeve 5| formed of hard rubber, metal,fiber, or other material, this tendency towards binding is almostentirely avoided.

Instead of providing a cylinder or sleeve 5| of metal or fiber, or someother material, the rubber rotor 50 may be treated in a particularmanner so as to accomplish a substantially similar result. Thus, forexample, while the inner surface on which the teeth of the rotor areformed may be relatively resilient and compressible, the outer surfacemay be compounded and treated of rubber so as to form a very strong,hard rubber which strongly resists distortion and which also slidesfreely within the housing,44

A further modification of my pump is illustrated diagrammatically inFigure 11 in which I have indicated at 52 in full lines the outline of apinion or an impeller whose teeth 6|! are strictly conjugate to thetooth form of the rotor 50. I prefer to modify the tooth contour of thepinion or impeller 52 by relieving or cutting away the same intermediatethe teeth 60 such relief being shown at 6|. This, as will be readilyappreciated,

of the teeth of the rotor 50, which would otherwise engage in slidingcontact therewith.

This relief is on the order of .030 of an inch or, in other words,considerably larger than the relative oversize condition existingbetween the rotor till-and the-pinion or impeller 52. Consequently, evenwith the oversize condition referred to, the relief at El will provideclearance under all conditions. This clearance 'is important inoperating conditions where foreign matter, as for example grains of sandor the like, are carried by the fluid being pumped. It will beappreciated that the flow of fiuid through the pump is axially withrespect to the rotor 50 and pinion 52; that is, the fluid is introducedfrom one end between the gears and flows out, either from the same endor from the other end. In the embodiment illustrated, valve openings arepreferably provided in the surfaces of the plates M and 42 to increasethe capacity of the pump. Accordingly, sand which may be introduced intothe pump in most cases is never introduced between the tips of the teethBI] and the compressible material of the rotor 50. However, in caseswhere the sand may be thus included, it will merely be embedded in therubber and will subsequently be expelled from the pump without causingpermanent injury to the parts.

Referring again to Figure 10, itwill be noted that the cylinder orsleeve 5| is of less width than the rotor 50 so that the rotor tillextends beyond the edges of the cylinder or sleeve 5|, as indicated at62. This is an important structural assists to enable those skilled inthe art to practice the invention, the scope of which is indicated bythe appended claims. 5 r What I claim as my invention is: i

1. In a. pump of the character described, a

cylindrical housing having fluid inlet and outlet-,- ports at an endthereof, an annular, internally toothed rotor having an outerv smoothcylindrical surface closely fitting within said housing, the

outer surface of said rotor being adapted strongly to resist distortion,the internally toothed portion nally toothed rotor formed of resilient,com

.rotor meshed internally therein, said pinion being slightly oversizeradially with respect to saida rotor and being formed 01 substantiallyincomieature, since it permits the end surfaces of the rotor which areformed of resilient, compressible material, as hereinbefore described,to engage directly and sealingly with the surfaces of the end plates orclosures 4| and 42. This substantially increases the effectiveness ofthe seal without at the same time requiring highly accurate machining.If desired, slight pressure may be exerted between the plates 4| and 42on the end surfaces 63 of the rotor 50.

It may be mentioned that the amount of adjustability provided for thehousing 44 may be very slight, and adjustments of more than .010 of aninch is seldom required.

I have found that a pump constructed according to the present teachingsofiers another important advantage in that it runs with almost perfectquietness. This will be readily appreciated since it will be seen thatonly rotary parts are employed and that all engaging surfaces whichmight produce noise provide a metal to rubber or metal to otherresilient material contact. The pump disclosed herein is capable of manyapplications and it will be understood that according to the fluid forwhich it is designed the materials may be selected so as to operateefiiciently therewith. Thus for example, I have found that while rubberis highly efficient as a resilient material, in some cases it isdesirable to substitute another resilient material which will not beadversely affected by the fluid being pumped. I, therefore, wish itclearly understood that I do not desire to be specifically restricted torubber as a material but that other resilient materials may be employedwithout departing from the scope of my invention.

This application is a continuation in part of my prior copendingapplication, Serial No.21'7,- 524, entitled Rotary pump, filed July 5,1938.

While I have illustrated and described two specific embodiments of myrotary pump, it will be understood that the same has been done solelypressible material whereby the teeth of said pinion will be embeddedslightly in the compressible material formhm the teeth of said rotor,and means for driving said pinion.

3. In 'a pump of the character described, a cylindrical housing havingfluid inlet and outlet ports at an end thereof, an annular, internallytoothed rotor formed of resilient, compressible material, a metalcylinder or ring surrounding and secured to said rotor and fittingsnugly within said housing, a driving pinion of lesser number of teeththan said rotor meshed internally therein, said pinion being slightlyoversize radially with respect to said rotor and being formed ofsubstantially incompressible material whereby the teeth of said pinionwill be embedded slightly in the compressible material forming the teethof said rotor, and means for driving said pinion.

4. In a pump of the character described, a cylindrical housing havingfluid inlet and outlet ports at an end thereof, an annular, internallytoothed rotor formed of resilient, compressible material, a cylinder orring surrounding and secured to said rotor and fitting snugly withinsaid housing, said ring being of a material adapted strongly to resistdistortion, said cylinder or ring being of slightly less axial extentthan said rotor, whereby said rotor may directly engage the end Walls ofsaid cylindrical housing, a driving pinion of lesser number of teeththan said rotor meshed internally therein, said pinion being slightlyoversize radially with respect to said rotor and being formed ofsubstantially incompressible material whereby the teeth of said pinionwill be embedded slightly in the compressible material forming the teethof said rotor, and means for driving said pinion.

5. In a pump of the character described, a

cylindrical housing having fluid inlet and outlet outer surface of saidrotor being adapted strongly to resist distortion, the internallytoothed portion of said rotor being formed of resilient compressiblematerial, a metallic driving pinion of lesser number of teeth than saidrotor meshed internally therein, said pinion being slightly oversizeradially with respect to said rotor whereby the teeth of said pinionwill be embedded slightly in the compressible material forming the teethof saidv rotor, and means for driving said pinion, said casing beingadjustable in a plane perpendicular to the axes of said rotor and pinionto vary the amount which the teeth of the pinion are embedded in thecompressible material forming the teeth of said rotor at one side ofsaid rotor.

6. A pump of the class described comprising a base, a plate rigidlysecured thereto, said base and plate being apertured, a drive shaftpassing through said apertures, a second plate secured to said base andfirst plate in spaced, parallel relation, a cylindrical housing mountedbetween said plates, an annular member having internal teeth formed ofcompressible, resilient material and an outer surface adapted stronglyto resist distortion rotatably mounted in said housing. a rigid drivingpinion carried by said shaft in said housing in meshing relation withsaid annular member. said housing being adjustable between said platesrelative to the axis of said shaft in a plane perpendicular theretowhereby the tips of the teeth of said pinion may be embedded differentamounts as desired in the compressible resilient material of the teethat one side of said annular member.

"I. A pump of the class described comprising a base, a plate rigidlysecured thereto, said base and'plate being apertured, a drive shaftpassing through said apertures, a second plate secured to said base andfirst plate in spaced, parallel relation, a cylindrical housing mountedbetween said plates, an annular member having internal teeth formed ofcompressible, resilient material and an outer shell of material adaptedstrongly to resist deformation rotatably mounted in said housing for'free rotation, a rigid driving pinion carried by said shaft in saidhousing in meshing relation with said annular member, said housing beingadiustable between said plates relative to toothed rotor having an outersmooth cylindrical surface closely fitting within said housing androtatably mounted therein, the internally toothed ,portion of said rotorbeing formed of resilient compressible material and the outer surface ofsaid rotor being adapted strongly to resist distortion, a rigid drivingpinion of lesser number of teeth than said rotor meshed internallytherewith, means for driving said pinion, and means for adjusting saidhousing together with said rotor relative to said pinion in a planeperpendicular to the axes of said rotor and pinion to cause the tips ofsaid p'inion teeth to become embedded a desired amount in the resilientcompressible material of the internally toothed portion of said rotor.

9. A pump comprising a cylindrical housing having spaced inlet andoutlet ports in an end of said housing; an annular, internally toothedrotor rotatably mounted in said housing, the inner or toothed portion ofsaid rotor being resilient and compressible, the outer surface of saidrotor being adapted strongly to resist distortion;

a driving pinion having one less 'tooth than said rotor meshedinternally therewith and forming pumping chamber therebetween; saidchambers passing over and registering alternately within said inlet andoutlet ports during rotation of 'said rotor and pinion, the teeth ofsaid pinion the teeth of said pinion are slightly embedded in the innersurface of said rotor.

EUGENE SIBLEY.

